The analgesic compositions generally used for relieving a large variety of pain states contain two levels of codeine as the central acting agent and as the peripherally acting agent(s) acetaminophen or acetyl salicylic acid or combinations of these two agents. The most universal combinations come in two forms of either 30 or 60 mg of codeine with 300 mg of acetaminophen or 325 mg of acetyl salicylic acid. The most common composition contains the smaller amount of codeine since the larger the amount of codeine, the severer the side effects. It is the general belief that the smaller amount of codeine the less effective is the composition as an analgesic. However, there are compositions available with 300 mg of acetaminophen or acetyl salicylic acid and lower amounts of codeine such as 7.5 mg and 15 mg which are used for children or patients with small body weight. Nevertheless, over 99% of the use of "Codeine Combinations" consists of combinations including 30 or more mg of codeine, and the combination of 30 mg of codeine with 300 mg of acetaminophen represents about 90% of all usage of codeine combinations, reason for which we call it the "state of the art Codeine Combination".
U.S. Pat. No. 2,889,249 issued to Beiler et al. discloses a combination of codeine and aspirin with .alpha.-allyl-.alpha.-benzylacetamide. The most pertinent prior art is the combinations of codeine recited above.